In practice, such a device serves for simultaneous, for example parallel, processing of the workpiece by means of the parallel laser beams. In the case of a simple design, a semitransparent mirror is used as a beam splitter, which is followed in the beam path of at least one laser beam by a reflector in order to thereby generate a parallel beam path. Every laser beam is focused onto a common focusing plane on the workpiece by means of a focusing optical system.
A generic device has been disclosed in for example U.S. Pat. No. 6,103,990 A. Furthermore, devices with a beam splitter are also described in EP 06 24 424 A1 and U.S. Pat. No. 6,927,109 A1.
In practice, the desired, more particularly step-free, adjustability of the spacing between the laser beams was found to be problematic. For this, the reflector can have a moveable design with respect to the beam path of the other laser beam in order to thereby generate the desired spacing.
A disadvantage of this proposed solution was found to be that the change of the spacing was simultaneously connected to the change in the central position of the two laser beams, the latter change having to be compensated for by a superimposed displacement of the entire device. In particular, the laser beams have to be moved by a respectively differing amount, requiring corresponding separate drives in practice.
US 2006/0072207 A1 discloses a polarization filter that is subdivided by electromagnetic radiation into different linearly-polarized radiation. After a different number of reflections of the differently polarized radiation, the deflection in the same direction is brought about.
JP 59218292 A 1 relates to a beam splitter, wherein a lens and a reflector are arranged in the beam path of each partial beam for deflecting the respective partial beam into a common plane parallel to the focusing plane in the direction of mutually opposite deflection surfaces arranged between the reflectors. The deflection surfaces are respectively arranged tilted at an angle of 45° with respect to the focusing plane and are arranged such that they can be displaced perpendicularly to the focusing plane. This achieves step-free adjustment of the relative spacing between adjacent laser beams with an axis of symmetry remaining unchanged.